Drum machine

Because these early drum machines came out before the introduction of MIDI in 1983, they used a variety of methods of having their rhythms synchronized to other electronic devices. Some used a method of synchronization called DIN-sync, or sync-24. Some of these machines also output analog CV/Gate voltages that could be used to synchronize or control analog synthesizers and other music equipment.

Drum machines can either be programmed in real time (the user hears a metronome and plays beats in time with the metronome) or in step time, where the user specifies the precise moment in time on which a note will sound. By stringing differently-programmed bars together, fills, breaks, rhythmic changes, and longer phrases can be created. Drum machine controls typically include Tempo, Start and Stop, volume control of individual sounds, keys to trigger individual drum sounds, and storage locations for a number of different rhythms. Most drum machines can also be controlled via MIDI.

By the year 2000, standalone drum machines became much less common, being partly supplanted by general-purpose hardware samplers controlled by sequencers (built-in or external), software-based sequencing and sampling and the use of loops, and music workstations with integrated sequencing and drum sounds. TR-808 and other digitized drum machine sounds can be found on archives on the Internet. However, traditional drum machines are still being made by companies such as Roland Corporation (under the name Boss), Zoom, Korg and Alesis, whose SR-16 drum machine has remained popular since it was introduced in 1991.

There are percussion-specific sound modules that can be triggered by pickups, trigger pads, or through MIDI. These are called drum modules; the Alesis D4 and Roland TD-8 are popular examples. Unless such a sound module also features a sequencer, it is, strictly speaking, not a drum machine.